General Science Question Answers Chapter 20 Class 7 Maharashtra Board

Question Answers For All Chapters – General Science Class 7

In the World of Stars

Exercise

1. Fill in the blanks:

(a) When seen from a great distance, the sky seems to be touching the ground along a circle. This circle is called the horizon.

(b) The ecliptic is used while defining the zodiac signs.

(c) Classified according to seasons, one season will have nine nakshatras.

(d) The rising of the sun in the east and its setting in the west is the apparent motion of the sun.

2. A star rises at 8 PM tonight. At what time will it rise after a month? Why?

→ A star rises 4 minutes earlier every day.→ After a month (30 days), it will rise 30 × 4 = 120 minutes (or 2 hours) earlier.→ So, after a month, the star will rise at 6 PM.

3. What is meant by ‘The sun enters a nakshatra’ ? It is said that in the rainy season the sun enters the Mrug nakshatra. What does it mean?

→ When we say “the sun enters a nakshatra,” it means that from the earth, the sun appears to be in front of a particular star group (nakshatra) in the sky.

→ Example: In the rainy season, we say the sun enters Mrug nakshatra, meaning the sun appears to be in the direction of the Mrug (Orion) constellation.

4. Answer the following questions:

(a) What is a constellation?

→ A constellation is a group of stars that form a recognizable pattern in the sky.→ Example: Saptarshi (Great Bear), Orion (Mrug), and Scorpio (Vrushchik).

(b) What points should be considered before a sky watch?

1. Choose a place away from city lights for a clear view.
2. New moon nights are the best for star gazing.
3. Use binoculars or telescopes for better observation.
4. Identify the Pole Star as a reference point.
5. Begin by watching stars in the west, as they set earlier.

(c) Is it wrong to say that the planets, stars, and nakshatras affect human life? Why?

→ Yes, it is wrong because science has proven that celestial objects like planets and stars do not influence human life.→ Holding on to superstitions based on astrology is a waste of time, energy, and money.

5. Write a paragraph on the birth and lifecycle of stars using figure 20.1

Answer :

Stars are born from nebulae, which are large clouds of hydrogen gas and dust.

Due to gravity, these clouds contract and become dense and hot, forming a new star.

The star goes through different stages in its lifecycle, such as:

• Red Giant (expanding star)
• Supernova (exploding star)
• Neutron Star or Black Hole (final stage of a massive star).